ESD FR4 Epoxy Glass Fabric Laminated Sheet

What Does the Color of FR-4 Mean?

FR-4, the widely used epoxy glass cloth laminate, is well known for its excellent mechanical strength, flame resistance, and electrical insulation. While most people associate FR-4 with the typical green color seen in printed circuit boards (PCBs), FR-4 is actually available in several different colors, including yellow, white, black, and natural (light green or beige). But what do these colors really mean?

 

What Does the Color of FR-4 Mean

 

Green FR-4 – The Industry Standard

Most common in PCB manufacturing

Color often comes from the solder mask, not the laminate itself

Standard for consumer electronics and general applications

Offers balanced mechanical, thermal, and electrical properties

 

Yellow FR-4 – Cost-Effective and Visible

Often used in low-cost electrical insulation applications

Slightly lower aesthetics, but similar core properties

Offers high visibility in production environments

May be used where cost and visibility are prioritized

 

Black FR-4 – High-End Appearance

Popular in aerospace, automotive, or consumer tech requiring sleek design

Requires carbon black pigments, which may slightly affect flame retardancy

Often customized for structural or decorative insulation applications

 

White or Beige FR-4 – Optical and Clean Applications

Used in LED lighting, medical devices, or cleanroom environments

Enhances light reflectivity

May have lower Tg (glass transition temperature) unless formulated specifically

 

Do Colors Affect Performance?

While the base resin and glass cloth largely define FR-4’s performance, color additives or fillers can influence properties slightly:

Flame retardancy might be lower in heavily pigmented materials like black

Thermal conductivity or Tg can vary slightly depending on formulation

Surface resistivity or insulation resistance may be impacted in optical-grade white materials

 

Tip for Engineers & Buyers

Always check the datasheet, not just the color. Different manufacturers may use similar colors but vary in resin systems, Tg ratings, or compliance (such as RoHS or UL 94V-0).

 

YILONG supply FR-4 laminates in custom colors and grades to match your technical and visual requirements. Whether you need high-Tg black boards for structural support, or white FR-4 for lighting systems, we can tailor the solution to fit.

For technical specifications or sample requests, contact us at yilong@yilonginsulation.com.